Direct Identification and Characterization of Marine Heterotrophic Nitrogen Fixers by Stable Isotope Probing

通过稳定同位素探测直接识别和表征海洋异养固氮剂

• 批准号: 1341178
• 负责人: Douglas Capone
• 金额: $ 29.98万
• 依托单位: University of Southern California
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-06-01 至 2016-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1341178&HistoricalAwards=false
• 关键词: Direct; Identification; Characterization; Marine; Heterotrophic

The nitrogen cycle in the ocean is extremely complex and it continues to yield surprises. Knowledge gained in this project will directly contribute to resolving an unsettled and important question regarding the sources of nitrogen in the oceans because imbalances in nitrogen budgets have raised questions on how well we have quantified all nitrogen inputs and removal. While nitrogen-fixing cyanobacteria have long been recognized as important contributors to nitrogen fixation in the oceans heterotrophic nitrogen-fixing bacteria (HNFB) are a poorly characterized, but potentially important, component of the marine nitrogen-fixing community. Using advanced methodologies, this project will develop the means to obtain a new understanding of novel, active, HNFB in the ocean. The identification of these organisms and the assessment of their phylogenetic diversity and biogeochemical significance will provide important insights about their role in the marine nitrogen cycle. The project will develop a novel stable isotope probing (SIP) methodology coupled with high-throughput sequencing. SIP exploits the uptake of isotopically enriched substrates into nucleic acids (e.g., DNA) while high-throughput sequencing should allow the identification of nitrogen-fixing bacteria generally, and HNFB specifically, so that the principal investigator can directly link the biogeochemistry of nitrogen with the phylogeny of those nitrogen-fixers. The objective of this project is to provide a proof of concept effort and identify important HNFB lineages using this novel approach and begin to develop quantitative estimates for the contribution of HNFB populations to marine nitrogen-fixation and the nitrogen cycle. This project will foster the development of a graduate student who will work on all aspects of the project for his PhD and the work will be presented at science conferences and in public outreach venues. Undergraduates will also work on the project under the guidance of the graduate student and principal investigator. The participants will also engage with the USC Young Researchers Program (YRP), which recruits high school students from diverse and underprivileged local schools for summer research experiences. Students will be guided in the laboratory-based aspects of this project, and present their work at an YRP symposium. The principal investigator will also continue to participate in science curriculum development workshops of the Center for Ocean Sciences Education Excellence-West program.

海洋中的氮循环非常复杂，并且继续产生惊喜。该项目中获得的知识将直接有助于解决有关海洋中氮来源的不安而重要的问题，因为氮预算的失衡已经提出了有关我们如何量化所有氮输入和去除的问题。虽然长期以来，固定氮的蓝细菌已被认为是海洋异构氮固定细菌（HNFB）的氮固定的重要贡献者，但它具有很差的特征，但潜在的重要但可能很重要，但是固定氮的组成部分。使用先进的方法，该项目将开发出对海洋中新型，活跃的HNFB的新理解的方法。这些生物的鉴定以及对它们的系统发育多样性和生物地球化学意义的评估将为它们在海洋氮周期中的作用提供重要的见解。该项目将开发一种新型的稳定同位素探测（SIP）方法，并结合高通量测序。 SIP利用同位素富集底物摄取到核酸（例如DNA）中，而高通量测序应允许通常鉴定氮固定细菌，而通常是特定的HNFB，以便首主研究者可以将氮基因与这些NINROGEN-NINROG-fix-nitrogen-nitrogen-nitrogen-nitrogen-nitrogen-fix链接起来。该项目的目的是提供概念努力的证明，并使用这种新方法来确定重要的HNFB谱系，并开始为HNFB种群对海洋氮固定和氮气的贡献进行定量估计。该项目将促进研究生的发展，该研究生将在该项目的各个方面为其博士学位工作，该工作将在科学会议和公共宣传场所介绍。本科生还将在研究生和首席研究员的指导下从事该项目。参与者还将与USC青年研究人员计划（YRP）互动，该计划将招募来自多元化和贫困当地学校的高中生，以获得夏季研究经验。学生将受到该项目基于实验室的方面的指导，并在YRP研讨会上介绍他们的工作。首席研究人员还将继续参加海洋科学教育卓越计划中心的科学课程开发研讨会。